Reversible Reactions

What is a key characteristic that distinguishes an irreversible reaction from a reversible reaction?

• Irreversible reactions always release heat, while reversible reactions absorb it.

• Irreversible reactions proceed in one direction, converting reactants to products without returning to reactants.

• Reversible reactions require a catalyst, whereas irreversible reactions do not.

• Irreversible reactions involve only physical changes, while reversible reactions involve chemical changes.

Which chemical reaction did Claude Berthollet observe in Egyptian lakes, leading to his discovery of reversible reactions?

• Combustion of wood into carbon dioxide and water.

• Formation of sodium carbonate and calcium chloride from sodium chloride and calcium carbonate.

• Evaporation of water into water vapor.

• Binding of molecules to olfactory neurons.

In a reversible reaction, what defines a state of equilibrium?

• The reaction stops completely, and no further changes occur.

• The concentration of reactants becomes zero, and only products remain.

• The rate of the forward reaction equals the rate of the reverse reaction, leading to no net change in reactant or product amounts.

• The temperature of the system continuously increases until all reactants are consumed.

How does the sense of smell exemplify a reversible reaction in biology?

• Olfactory neurons permanently change their structure after detecting a smell.

• Molecules bind to olfactory receptors, triggering a neural impulse, and then unbind, allowing for detection of new smells.

• The brain continuously processes the same smell until it adapts and ignores it.

• Smell molecules are chemically altered by the olfactory bulb, preventing further detection.